Slide changing device for slide projectors

ABSTRACT

A slide projector includes means for receiving a vertical slide stack. A device for indexing the lowermost slide to a film gate and then to a receptacle for receiving viewed slides includes a first slide member which is movable vertically past the gate to push slides out of the gate toward the receptacle. A second slide member is movable horizontally to index the lowermost slide of the stack to a chute. The slide drops along the chute into the film gate. The first and second slide members are interconnected so that movement of the first slide member in a vertical direction moves the second slide member in a horizontal direction.

United States Patent [191 Hiipener et a].

SLIDE CHANGING DEVICE FOR SLIDE PROJECTORS Inventors: Clemens Hiipener,Ruit; Wolfgang Ort, Stuttgart-bad Cannstatt, both of Germany EastmanKodak Company, Rochester, NY.

Filed: Nov. 26, 1971 Appl. No.: 202,359

Assignee:

Foreign Application Priority Data Jan. 22, 1971 Germany P 21 02 927.6

References Cited UNITED STATES PATENTS 3/1967 Antos 353/112 [4 1 Feb. 5,1974 2,922,335 l/l960 Lacoe 353/112 3,495,902 2/1970 Michniewicz 353/112FOREIGN PATENTS OR APPLlCATlONS 1,142,710 4/1957 France 353/112 PrimaryExaminer--Harry N. Haroian [5 7] ABSTRACT A slide projector includesmeans for receiving a vertical slide stack. A device for indexing thelowermost slide to a film gate and then to a receptacle for receivingviewed slides includes a first slide member which is movable verticallypast the gate to push slides out of the gate toward the receptacle. Asecond slide member is movable horizontally to index the lowermost slideof the stack to a chute. The slide drops along the chute into the filmgate. The first and second slide members are interconnected so thatmovement of the first slide member in a vertical direction moves thesecond slide member in a horizontal direction.

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SHEET 5 OF 6 CLEMENS H6PFNER "WOLFGANG ORT ATTORNEYS PATENTED FEB 51974SHEET 5 BF 6 CLEMENS H6PF- WOLFGANG 0R1 v INVENTORS ATTORNEYS ERFQUESBPmmm 519M SHEET W CLEMENS H6PF-ER WOLFGANG ORT I EmoRs f TTORNEYS SLIDECHANGING DEVICE FOR SLIDE PROJECTORS BACKGROUND OF THE INVENTION 1.Field of the Invention The invention relates to a device for viewingslide transparencies, and more particularly to an image changing devicefor a slide projector.

2. Description of the Prior Art Slide changing devices for projectorsare known in the art. Many such devices include a mechanism for takingthe lowermost slide from a stack of slies, for moving that slide to aprojection gate and for then indexing the viewed slide to a receptaclespaced either below or laterally of the gate. Some such devices aredescribed in US. Pats. Nos. 2,503,239 which issued Apr. 11, 1950 toJoseph Antos and 3,495,902 which issued Feb. 17,!970 to EdwardMichniewicz and in French Pat. No. 1,412,710 in the name of M. RogerFlipo.

The apparatus shown by Michniewicz includes a mechanism for changingslides at the projection gateby pushing the viewed slide out of the gateby means of the incoming slide. Such a device could result in damagedslide mounts and possibly in blockage of the mechanism. In the Antos andF lipo patents, projectors are arranged so that slides drop toward thegate by gravity. In the Flipo patent, once a slide nears the gate, it isdriven the rest of the way by a roller, thereby increasing the risk ofjamming of the mechanism. The Antos mechanism permits 'an incoming slideto drop completely into the gate and, after viewing, to then drop to thereceptacle. Since the mechanism includes no positive means of removingaslide from the gate, slides in damaged mounts may get jammed in thegate.

SUMMARY OF THE INVENTION I According to one feature of the presentinvention, a slide member is mounted on a projector for movement betweena first position and a second position along a path parallel to andbelow a stack of slides to move the lowermost slide laterally from thestack to a position above a film gate. A member on the slide membermoves to a position below the film gate, as a slide is being removedfrom a stack for catching a slide as it moves into the gate by gravity.

According to another feature of the present invention, the slide memberincludes means for supporting the leading edge of the lowermost slide asthat slide is removed from the stack. Abutment means stop the lateralmovement of the slide whereby the supporting means moves beyond theleading edge to permit the slide to drop toward the gate.

According to yet another feature of the present invention, a secondslide member is movable vertically past the film gate to push a viewedslide out of the gate, and meansare provided for interconnecting the twoslide members in perpendicular directions whereby a viewed slide isremoved from the gate as the next slide is moved laterally from theslide stack.

The invention, and its objects and advantages, will become more apparentin the detailed description of the preferred embodiment presented belowin conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS In the detailed description of thepreferred embodiment of the invention presented! below, reference ismade to the accompanying drawings in which:

FIG. 1 is a perspective view of a slide projector according to thepresent invention;

FIG. 2 is an exploded view, partially broken away, of a slide containerfor use with the projector of FIG. 1;

FIG. 3 is a top view of the slide container shown in FIG. 2;

in FIG. 1; a

FIG. 7 is an enlarged view of a portion of FIG. 6;

FIG. 8 is a perspective view of a portion of the projector of FIG. 1;

FIG. 9 is a perspective view of a portion of the projector of FIG. 1; l

FIG. l0is a view, partially in section, of a part of the slide changingdevice in the image position;

FIG. 10A is a view similar to FIG. 10 showing the elements while thelowermost slide is being removed from the stack; and i y 1 FIG. 10B is aview similar to FIGS. 10 and 10Ashowing the elements as the lowermostslide is released for movement toward the film gate.

DESCRIPTION OF THE PREFERRED EMBODIMENT Because projectors are wellknown, the present de scription will be directed in particular toelements forming part of, or cooperating more directly with, apparatusin accordance with the present invention. It is to be understood thatprojector elements not specifically shown or described may take variousforms well known to those skilled in the art. I i

FIG. 1 shows a projector 10 having a lens 12, a folding lid 14 whichcovers a slide receiving means, a lateral wall 16 with a flap 18covering an access opening to the illumination device, a recess 19 withan operating key 20 of a slide changing device and a rhomboidal aperture22 in a take-up chamber 24;

FIGS. 2 and 3 show a slide container with a base 26 and a lid 28. Thefront wall of base 26 is provided with a recess 30, so that only twowall portions 32 and 34 are left. A lateral wall 36 has two, slightlyconcial plugs 38 and 40. A rear wall 42 projects rearwardly and itsupper edge 44 terminates at a slightly lower level than the edges of theother walls. The base accommodates a slide stack 46.

Lid 28, which has been detached from base 26 in the direction of arrow Ahas a viewing; lens 48 disposed in its front wall 50. The rear wall 52has a bulge 54 which is adpated to serve as a focusing screen. A lateralwall 54 is provided with two bores 56 and 58 as well as with a guideportion 60 which is arranged along the wall at a distance of about oneand a half times the thickness of a slide mount from the point where thelateral walls meet the rear wall 52. A similar guide portion 62 isarranged on lateral wall 64. These guide portions extend from the bottomwall 66 of lid 28 up to about half of the height of the surrounding wallso that one guide groove 68 and 70 each is formed (FIG. 3).

For enabling a viewing of the slides, base 26 and lid 28 of the slidecontainer are attached to each other in side-by-side relation with plugs38 and 40 inserted into bores 56 and 58, respectively, to form a unit.Each time the lowermost slide 46a is withdrawn from base 26 and insertedin guide grooves 68 and 70, the stack may be moved forward so that theviewed slide can be restored after viewing to base 26 between rearwardlyprojecting rear wall 42 and the last slide of stack 46.

When lid 28 is placed back onto base 26, the upper edge 72 of thelateral wall 64 of the lid rests on plugs 38 and 40. Likewise, rear wall42 of the base with its upper edge 44 rests on the upper edges 74 and 76of the two guide portions 62 and 60, respectively. I

In FIGS. 4 and 5, the base 26 of the slide container is shown insertedinto the container receiving means 80 located above a film gate 82 andthe optical axis 84 with the recessed front 32 pointing downwardly. Nowthe upwardly folded lid 14 serves as a stop for slides 46 stacked inbase 26. A bottom plate 86 on which base 26 is located has a step 86a,to whose edge 86b the edge of the wall of base 26 corresponds. Followingthe step, bottom plate 86 extends downwardly in an oblique direction andforms a front wall 88 of a passageway leading to a chute 90. The wall ofsaid passageway is contined in a vertical direction and is provided withprojection aperture 92 at the level of optical axis 84, endingapproximately in the center of the projector. Below projection aperture92, the front of wall 88 is provided with U-shaped retaining spring 94which is designed in such a manner that its lower part projects beyondwall 88 and prolongs the chute in downward direction (FIGS. 4 and 9).Each of the upper edges of the two legs of the spring comprises aresilient tongue 94a and 94b and a bent lug 94c and 94d (FIGS. 6, 8, and9).

As appears further from FIGS. 4 and 5, the inside of the upper housingwall of the projector comprises a stopping edge 96. Below this stoppingedge begins the lower wall 98 of the passageway leading to chute 90,said wall extending downwardly in an oblique direction. Wall 98 is alsocontinued in a vertical direction and is equally provided with aprojection aperture 100 at the level of the optical axis 84. Theprojection apertures of both walls including the retaining spring 94form the film gate with is referred to by numeral 82. Rear wall 98 isthen continued below film gate 82 and forms the bottom 102 of take-upchamber 24 in which lid 28 of base 26 which is attached above the filmgate is inserted.

As appears in particular from FIG. 9, the slide changing device consistsof two slide members 104 and '106 which are arranged transversely ofeach other. The first slide member 104 is provided at its narrow sidefacing second slide member 106 with a bolt 108 which, as will bedescribed below, becomes effective in a guide groove 110 of the secondslide member 106. First slide member 104 carries at its other narrowside operating key and is seated in front wall 88 of the film gate to bedisplaceable in the direction of arrow B contrary to the bias of aspring (not shown). In its upper half it is provided with two cams 112acting on the two resilient tongues 94a and 94b during the displacingprocess. An engaging pawl 114 is rotatably mounted by means of afriction bearing pin 116 approximately in the center of the slide member(FIGS. 4 and 6). It is a two-armed pawl, one arm 118 projecting intochute with its downwardly directed nose 120, whereas the other arm 122extends with its rounded off, upwardly directed nose 124 in the oppositedirection out of a recess 126 of the first slide member 104. Above thepawl arrangement, slide member 104 is recessed on the side 128 whichfaces the chute (FIG. 8). In a recess 130, a cover plate 132 isdisplaceably seated by means of a pin-slot connection 134 and 136. Atits lower edge, it has a stop 138. In the vicinity of actuating key 20,a locking pawl of a reversal prevention means is arranged. It is mountedto be rotatable about collar screw 142 and it has a bent stop nose 144which is abutted against by the free leg of a spring 146, keeping pawl140 in the position shown in FIG. 6, stop nose 144 projecting into anupper recess 148 at the inside of a lateral wall 150 of the projector.Inside of lateral wall 150 is provided further below with a secondrecess 152, and between the two recesses 148 and 150 with a toothedportion 154. The lateral wall further comprises a cam 156 carrying anattenuating cylinder 158 which is placed into functional connection witha bore 160 arranged in slide member 104 below pawl 140.

Second slide member 106, whose main portion is formed by a plate, ismovably supported at a bar 162 arranged at the inside of the lateralwall 164 of the projector. For this purpose two pins 166 (FIGS. 6, 7 and10) are arranged at the rear side of slide member plate 106 by whichslide member 106 is attached to bar 162. Pins 166 rest on the upper edge168 of bar 162 for sliding thereon during the motion of the slidemember. Bar 162 is further provided with two collar screws 170 (FIGS. 4and 7) projecting through a horizontal slot 172 in the upper half ofslide member plate 106, so that they are secured against dropping off.In the area where the upper edge of slide member plate 106 meets thefirst slide member 104 it comprises a bent finger whose upper surface174 serves as a slide support. The rearward portion of the upper edge ofthe slide member carries a lug 176 whose end is bent upwardly and isprovided with a driving plate 178. In the area of the lower half, partof the slide member plate is bent at a right angle. The bent portion180, which carries a stop nose 182 on its surface, has the shape of afork whose prongs 184 and 186 are directed towards film gate 82. Curvedguide groove 110 extends in the disk-shaped main portion from theleft-hand side at the top of the center at the bottom. In this guidegroove, bolt 108 of the first slide member 104 is vertically movable. Ifupon actuation of the slide members, the first slide member 104 is movedin the direction B, the second slide member 106, which is controlled viaguide groove 1 10, is moved in horizontal direction indicated by arrowC. When first slide member 104 is restored to its upper initialposition, second slide member 106 is automatically returned into itsinitial position contrary to the direction indicated by arrow C.

This reciprocating motion of second slide member 106 is performed in twoplanes. As is shown in FIGS.

6, 7 and 10, a control plate 188 is located between second slide member106 and the inside of lateral wall 164 of the projector and rests on theupper edge 168 of bar 162. The inside of the lateral wall 164 of theprojector is provided with four pins 190, of which always two arearranged in superposed relation and extend into two slots 192 at therear side of control plate 188. These pin-slot connections are designedin such a manner that control plate 188 can be moved upwardly in thedirection of arrow G. At the lower edge of the front of the controlplate two extended cams 194 and 196 are disposed, each of which has aninclined surface (198 and 200) at the front and one (202 and 204) at theback.

Operation of the apparatus is effected as follows: As has been describedabove, the base portion 26 ofthe slide container is inserted intocontainer receiving means 80 with the recessed front facing downwardly.Now top 28 is inserted into take-up chamber 24 through rhomboidalaperture. 22. A nose 206 arranged in the upper corner of aperture 22(FIGS. 1 and 4) ensures that cover 28 is inserted in the properposition. The cover first slides over the sloping insertion surface 208of a rib 212 arranged on bottom 102 of take-up chamber 24 and is placedbehind the steeper inclination 212. Owing to the breadth of rib 212, acorrect orientation of cover 28 relative to the optical axis is ensured.If first slide member 104 is moved by way of actuating key 20 verticallyin the direction of arrow B, second slide member 106 is displaced in thedirection of arrow C by the bolt and guide groove 108 and 110. Duringthis displacing motion, slide member 106 slides on the upper edge 168 ofbar 162 by means of its two pins 166. During this process, the pinsreach the inclined surfaces 198 and 200 of cams 194 and 196 which arearranged at control plate 188. Slide member 106 is lifted in thedirection of arrow F (FIGS. and 10A) by the thickness of cams 194 and196 and continues to move on the, upper edges 214 and 216 of the cams inthe direction of arrow C. In doing so, its drive plate 178 enters recess30 in the front wall of base portion 26 of the container, pushing thelowermost slide 460 out of the base portion. The front edge of saidslide is placed on support 174 of the slide member and remains in thehorizontal position until it abuts against the edge 96 of the housingbecause the other half of the 'slide'rests on the lower front wall ofthe container.

Shortly before the front edge of the slide strikes against stop 96 ofthe housing, the front of driving plate 178 reaches edge 86b of steppedbottom surface 86 and 86a. This corresponds to the position of plug 108in FIG. 10A, by the vertical movement of which the second slide member106 has covered a first long distance a in the direction of arrow C.During the following travel along path b of the guide groove (FIG. 10)the movement of the slide member in the direction of arrow C is brieflyinterrupted and the slide has sufficient time for dropping with its rearedge on step 86a. In the path c of the guide groove, the second slidemember 106 is moved for another short distance until support 174 isplaced behind stopping edge 96 of the housing. Then only may the slidedrop freely for reaching the film gate 82. This is illustrated in FIG.10B.

During the travel along the short path 0 the second slide member 106leaves with its pins 166 cams 194 and 196 and drops back onto the upperedge 168 of bar 162 (FIGS. 6 and 10B). During the return movement, thepins travel on this edge 168, lifting the control plate 188 in thedirection of arrow G by the rear inclined surfaces 202 and 204 of thecams. By this return move ment of slide member 106, which is performedat a level which is lower by the thickness of a cam, driving plate 178is returned below slide stack 46. When the initial position has beenreached, pins 166 leave the lower edges of the cams, so that controlplate 188 may drop back onto bar 162 and the cycle of operations isrepeated during a renewed movement of the slide member (FIG. 10).

FIG. 6 shows the manner in which nose 144 of locking pawl strikesagainst an inclined surface 218 of toothed portion 154 at the housingwhen the first slide member 104 is moved in the direction of arrow B andhow it is turned in the direction of arrow D contrary to the bias ofspring 146. As soon as nose 144 of the pawl skips the first tooth oftoothed portion 154, a reversal of the motion of the slide member is nolonger possible. Only when recess 152 at the lower end of toothedportion 154 has been reached, locking pawl 140 is pivoted out of itslocking position by spring 146. When the ac tuating key 20 is freed, andwhen slide member 104 is returned to the initial position by a tensionspring (not shown), nose 144 of the pawl reaches an inclined surface 220of toothed portion 154 and is moved into the position shown in FIG. 6 bya dash-dotted line, so that the locking effect is reversed.

During this movement of the first slide member 104 in the direction ofarrow B and while the second slide member 106 passes along the long patha (FIG. 10A), the downwardly directed nose 120 of engaging pawl 1 14 atthe first slide member 104 is placed on the upper edge of a precedingslide located in film gate 82, pushing it out of the projection position(FIG. 4). As has been mentioned already, the second slide member 106 ismoved in the section c of the guide path a small way in the direction ofarrow C, its support 174 being moved behind stop edge 96 of the housing(FIG. 10B) and the slide being released for dropping by gravity. By thismovement, also the two prongs 184 and 186 of fork 180 reach the droppingrange of the slide below the film gate 82, stop nose 182 of fork 180striking against arm 122 of engaging pawl 114, pivoting said pawl aboutfriction bearing pin 116 into the position shown in FIG. 5. Thus it isensured that during the upward motion of the first slide member 106, theslide which has dropped into the projection position is not touched. Inthe upper position of slide member 106, pawl 114 isrestored to theengaging position (FIG. 4) by a housing stop 22. Only after the twoprongs 184 and 186 have been moved into the receiving position belowfilm gate 82, the two resilient blades 94a and 94b are lifted by meansof the two slide cams 112 (FIG. 5) for enabling the already droppingslide to enter film gate 82. This is accomplished during the motionalong path a of the guide groove (FIG. 10).

When the first slide member 104 is depressed further by the amount d ofthe guide groove, piston 158 penetrates bore in slide member 104, asillustrated in FIG. 6. Thus the vertical movement of slide member 104 isdelayed and softly absorbed when it reaches the lowermost position. Atthe moment slide member 104 is released in that key 20 is no longerdepressed, the

. pneumatic braking device 160 and 158 effects a delayed initialrestoring motion. Thus the dropping slide has time enough to reach theprojection position before the resilient blades 94a and 94b are releasedagain by the slide member 104 returning in upward direction. Otherwisethe resilient blades would exercise a pressure on the dropping slide tooearly.

Another function of first slide member 104 consists in a masking of theray path during the exchange of slides. This is accomplished by means ofmask 132 (FIGS. 4, and 8). During the downward motion of the slidemember 104 it rests with its stop 138 on lugs 94c and 94d of U-shapedholding spring 94 and is kept in this position in which it covers thefilm gate, while slide member 104 ,moves downwardly by another portion.

All sides are successively collected in lid 28 (FIGS. 4 and 5). Said lidis ejected after slide display in the direction of insertion aperture 22via a round aperture 124 and is withdrawn from take-up chamber 24 forbeing combined again with base 26. At that stage, slide stack 46 isarranged in the slide container in the same order and position as beforethe display.

The invention has been described in detail with particular reference toa preferred embodiment thereof, but it will be understood thatvariations and modifications can be effected within the spirit and scopeof the invention.

We claim: 7

l. A slide changing device for a slide projector having a film gate andmeans above the film gate for receiving aplurality of slides arranged inthe form of a stack; said slide changing device comprising:

a slide member mounted on the projector for movement between first andsecond positions along a path generally parallel to the planes of theslides in the stack;

drive plate means on said slide member for (1) engaging the lowermostslide in the stack and (2) moving said lowermost slide laterally fromthe stack when said slide member moves toward said first position; 2

means defining a chute for guiding to said film gate a slide removedfrom the stack by said drive plate means;

means mounted on said slide member for movement to a position below saidfilm gate when said slide member is moved to its first position forreceiving a slide dropping through said chute; and

means for holding that slide at the film gate while said slide member isin its second position.

2. A slide changing device for a slide projector having a film gate andmeans above the film gate for receiving a plurality of slides arrangedin the form of a stack; said slide changing-device comprising:

a slide member mounted on the projector for movement between first andsecond positions along a path generally parallel to the planes of theslides in the stack;

drive plate means on said slide member for (1) engaging the lowermostslide in the stack and (2) moving said lowermost slide laterally fromthe stack when said slide member moves toward said first position;

means defining a chute for guiding to said film gate a slide removedfrom the stack by said drive plate means;

means on said slide member for supporting the leading edge of thelowermost slide in the stack as that slide is moved laterally by saidslide member moving toward said first position; and

abutment means for stopping said lateral movement of said lowermostslide before said slide member reaches said first position, whereby saidsupporting means moves beyond said leading edge to permit the slide todrop through said chute.

3. A slide changing device for a slide projector having a film gate andmeans above the film gate for receiving a plurality of slides arrangedin the form of a stack; said slide changing device comprising:

a drive plate having a leading edge, said drive plate being mounted onthe projector for movement l in a direction parallel to the plane ofslides in the stack between a first position wherein said leading edgeis behind and facing an edge of the lowermost slide in the stack and asecond position spaced from said first position in the direction facedby said leading edge and (2) in a direction perpendicular to said planesbetween positions respectively in and out of the plane of the lowermostslide;

means for moving said drive plate from its first to said second positionand from said second to said first position;

means for moving said drive plate (1) into the plane of the lowermostslide as said drive plate is moved from its first to its second positionand (2) out of the plane of the lowermost slide as said drive plate ismoved from its second to its first position.

4. A slide changing device for a slide projector having a film gate andmeans above the film gate for receiving a plurality of slides arrangedin the form of a stack; said slide changing device comprising:

a slide member mounted on the projector for movement between first andsecond positions along a path generally parallel to the planes of theslides in the stack;

drive plate means on said slide member for (1) engaging the lowermostslide in the stack and (2) moving said lowermost slide laterally fromthe stack when said slide member moves toward said first position;

means defining a chute for guiding to said film gate a slide removedfrom the stack by said drive plate I means;

means for resiliently holding slides in the film gate;

a second slide member movable downwardly in a direction perpendicular tothe path of said first mentioned slide member for pushing slides out ofsaid gate; and

means interconnecting said first and second slide members for movingsaid first slide member toward said first position when said secondslide member is moved downwardly.

5. A slide changing device as defined in claim 4 further comprisingmeans to prevent reversal of movement of said second slide member untila slide has been completely pushed from the gate.

6. A slide changing device as defined in claim 4 further comprisingpneumatic means for damping movement of said second slide member.

1. A slide changing device for a slide projector having a film gate andmeans above the film gate for receiving a plurality of slides arrangedin the form of a stack; said slide changing device comprising: a slidemember mounted on the projector for movement between first and secondpositions along a path generally parallel to the planes of the slides inthe stack; drive plate means on said slide member for (1) engaging thelowermost slide in the stack and (2) moving said lowermost slidelaterally from the stack when said slide member moves toward said firstposition; means defining a chute for guiding to said film gate a slideremoved from the stack by said drive plate means; means mounted on saidslide member for movement to a position below said film gate when saidslide member is moved to its first position for receiving a slidedropping through said chute; and means for holding that slide at thefilm gate while said slide member is in its second position.
 2. A slidechanging device for a slide projector having a film gate and means abovethe film gate for receiving a plurality of slides arranged in the formof a stack; said slide changing device comprising: a slide membermounted on the projector for movement between first and second positionsalong a paTh generally parallel to the planes of the slides in thestack; drive plate means on said slide member for (1) engaging thelowermost slide in the stack and (2) moving said lowermost slidelaterally from the stack when said slide member moves toward said firstposition; means defining a chute for guiding to said film gate a slideremoved from the stack by said drive plate means; means on said slidemember for supporting the leading edge of the lowermost slide in thestack as that slide is moved laterally by said slide member movingtoward said first position; and abutment means for stopping said lateralmovement of said lowermost slide before said slide member reaches saidfirst position, whereby said supporting means moves beyond said leadingedge to permit the slide to drop through said chute.
 3. A slide changingdevice for a slide projector having a film gate and means above the filmgate for receiving a plurality of slides arranged in the form of astack; said slide changing device comprising: a drive plate having aleading edge, said drive plate being mounted on the projector formovement (1) in a direction parallel to the plane of slides in the stackbetween a first position wherein said leading edge is behind and facingan edge of the lowermost slide in the stack and a second position spacedfrom said first position in the direction faced by said leading edge and(2) in a direction perpendicular to said planes between positionsrespectively in and out of the plane of the lowermost slide; means formoving said drive plate from its first to said second position and fromsaid second to said first position; means for moving said drive plate(1) into the plane of the lowermost slide as said drive plate is movedfrom its first to its second position and (2) out of the plane of thelowermost slide as said drive plate is moved from its second to itsfirst position.
 4. A slide changing device for a slide projector havinga film gate and means above the film gate for receiving a plurality ofslides arranged in the form of a stack; said slide changing devicecomprising: a slide member mounted on the projector for movement betweenfirst and second positions along a path generally parallel to the planesof the slides in the stack; drive plate means on said slide member for(1) engaging the lowermost slide in the stack and (2) moving saidlowermost slide laterally from the stack when said slide member movestoward said first position; means defining a chute for guiding to saidfilm gate a slide removed from the stack by said drive plate means;means for resiliently holding slides in the film gate; a second slidemember movable downwardly in a direction perpendicular to the path ofsaid first mentioned slide member for pushing slides out of said gate;and means interconnecting said first and second slide members for movingsaid first slide member toward said first position when said secondslide member is moved downwardly.
 5. A slide changing device as definedin claim 4 further comprising means to prevent reversal of movement ofsaid second slide member until a slide has been completely pushed fromthe gate.
 6. A slide changing device as defined in claim 4 furthercomprising pneumatic means for damping movement of said second slidemember.